A facile spectroscopic method for measuring lignin content in lignocellulosic biomass
F. Lu et al. "A facile spectroscopic method for measuring lignin content in lignocellulosic biomass" Green Chemistry (2021) [DOI:10.1039/D1GC01507A]
Although measuring lignin contents is a routine operation for biomass compositional analysis in process development aiming at efficient utilization of woody biomass, it is still a challenging task requiring many steps, hazardous reagents, heating, and a significant time. A facile spectroscopic method, our CASA (Cysteine-Assisted Sulfuric Acid) method, was developed to quantify the lignin content of lignocellulosic biomass, based on an extraordinary system in which biomass samples are fully dissolved in 72% H2SO4 containing cysteine at 24 °C in 60 min. The lignin absorptivities were determined by using synthetic lignins to be 17.25 g‑1.L.cm‑1 for softwood lignin and 11.23 g‑1.L.cm‑1 for hardwood lignin and monocot lignin. Seven softwoods, six hardwoods and six monocots, were tested using the CASA method. A very good coefficient of determination (R2 = 0.95) was found between the CASA results and acid-insoluble lignin contents, and an even better R2 (0.98) was obtained when the CASA data were correlated with the total lignin contents.
Detailed notes and workflows for the lignin measurement method can be found in the Supplementary Information.